Insulator for neon sign letters



July 5, 1955 H. s. MATTHEWS INSULATOR FOR NEON SIGN LETTERS Filed Sept. 29, 1952 INVENTOR. #992 Y 5. MATT/{fwd BY United Fatent INSULATfiR FDR NEON SIGN LETTERS Harry S. Matthews, Detroit, Mich. Application September 29, 1952, Serial No. 312,069

4 Claims. (Cl. 174-153) This invention relates to insulators for neon sign letters. The gas-filled letters of neon or similar advertising signs consist of glass tubes having discharge electrodes at their terminal end portions through which a high voltage charge of electricity is discharged from one end of the sign letter to the other end thereof to render the neon or other gas luminous. These terminal end portions of the gas-filled tubes are normally bent at a right angle to the main portion of the tube, which is likewise bent to form the desired letter. The luminous letter is usually placed in front of a corresponding sign letter painted on the outer surface of a base plate or panel of the sign. Most neon signs consist of a pair of such base or face plates spaced from each other, and in the space between the face plates the electric wiring circuits and terminal connections thereof to the sign letters are housed.

One of the problems in connection with the neon advertising signs is that of properly insulating the sign letters and the electrodes contained therein from the grounded metal of the sign face or base plates. The common practice in the neon sign industry has been to provide an insulating sleeve of porcelain provided with a laterally projecting annular flange to engage the outer surface of the sign panel and having a tubular cylindrical portion which projects through the face plate of the sign. This inwardly projecting portion of the insulating sleeve is formed with relatively coarse screw threads adapted to be engaged by a flanged sheet metal sleeve having corresponding threads which is screwed on to the screw threads of the tubular portion of the porcelain sleeve to clamp theannular flange thereof securely against the front surface of the face plate of the sign.

As the sign letters must, in order to produce the desired result, be adjusted to'align with reasonable accuracy with the painted letters on the face of the sign, it becomes necessary to provide means for adjusting the luminous gas-filled sign letter in order to efiect the desired positioning thereof with respect to the painted letters on the face of the sign. Consequently it has been the more or less standard practice to provide the porcelain insulators with an oversized hole having a diameter much larger than the diameter of the tubular gas-filled sign letter.

Another form of insulator commonly used for neon advertising signs consists of a glass tubular sleeve closed at its inner end and also provided with external coarse screw threads and a laterally projecting flange for engaging the outer surface of the sign face plate. In this type of insulator a sheet metal flanged and screw-threaded locking member similar to that above described for use with the porcelain insulator is also provided. In both of these types of insulators the diameter of the hole passing therethrough is approximately an inch and a quarter, while the diameter of the glass tube which forms the sign letter is approximately five-eighths of an inch. Consequently, not only is the appearance of the physical outer face of the sign to a large extent marred by the large exposed holes of the insulators, but dirt, insects and other foreign matter may enter into the insulator holes and collect therein. This collection of dirt, insects, etc., within the insulators above described forms a constant hazard, particularly in wet weather when the accumulated foreign f2 matter becomes wet and therefore tends to build up a conductive path between the discharge ends of the sign letter electrodes and the grounded metal of the sign.

Due to the fact that the adjustment of the gas-filled sign letters relative to the painted letters on the face of the sign is essential for proper advertising effects, it is necessary to provide the large oversized holes in the insulators. In adjusting the illuminated letter relative to the painted sign letters, the gas-filled sign letter must be moved bodily both laterally and vertically to effect the desired adjustment and establish the required alignment of the luminous gas-filled letter with the painted sign letter.

I have found that when the discharge end of the metal electrodes in the terminal portions of the tubular gas-filled luminous sign letters is located within one-half inch, or less, of the metal sleeves, as above described, that are used to lock both the glass and porcelain insulators above described to the face plate of the sign, an arcing of the high voltage current across to the inner end of said sleeves is very likely to occur. When such arcing does occur, the high-voltage current commonly used for such signs punctures a hole in the glass tube and a tube failure occurs. This, as above pointed out, very frequently occurs during protracted spells of damp or rainy weather, thus necessitating great expense and trouble in the servicing of neon advertising signs.

The present invention has for its principal object to provide a new and improved insulator for use with neon advertising signs whereby the objectionable features of the insulators as hereinbefore pointed out will be entirely obviated.

Another object is to provide an insulator for the luminous gas-filled tubular letters of neon signs whereby the unsightly large apertures provided in the types of insulators as heretofore employed are eliminated.

Briefly, the insulator of the present invention is one wherein, instead of using a large oversized aperture, the insulator is provided with a central web portion provided with a relatively small hole in which the tubular terminal end portion of the luminous sign letter fits comparatively neatly with but only a suflicient amount of clearance to enable it to be slid fairly freely in order to make the requisite adjustments. The hole in the central web portion of the insulator is located eccentrically and the insulator is rotatably mounted and held within the oversized aperture at the face plate of the sign by metal clips, by means of which the insulator may be quickly and readily attached to or detached from the sheet metal face plate of the sign proper. These clips are preferably seated within re-entrant slots provided in the annular flange and the periphery of the cylindrical web portion of the insulator, all as will be pointed out more fully in the following more detailed description and by reference to the accompanying drawings forming a part hereof wherein:

Fig. 1 is a side elevation of an insulator constructed in accordance with the present invention attached to the face plate of an advertising sign;

Fig. 2 is a section on the line of Fig. 1;

Fig. 3 is a perspective detailed View of one of the retaining clips for holding the insulator in place on the face plate of the sign;

Fig. 4 is an enlarged detailed perspective view showing the slots in the periphery of the cylindrical web portion and annular flange of the insulator, together with reentrant recesses adjacent thereto in the outer face of said flange in which the terminal end portions of the clips shown in Fig. 3 are seated; and

Fig. 5 is a view also taken substantially on the line 2-2 of Fig. 1 showing the manner in which the insulator and retaining clips may be attached to or detached from the face plate the sign.

As shown in the drawings, the numeral it indicates a 3 face plate is provided with a plurality of oversized aperportion of the face plate of a eon advertising sign. This tures 11, it being understood that there will be two apertures 11 for each luminous gas-filled sign letter. Each of these oversized apertures is adapted receive an insulator such as indicated at 12, which is provided with a laterally projecting annular flange 13 and a cylindrical web por tion 14.

In accordance with the present invention the cylindrical web portion 14 of the insulator l2 projects but a comparatively short distance inwardly beyond the inner surface of the face plate it of the sign, for example, not more than three-eighths of an inch. This web portion is provided with an eccentrically located hole 15 through which the terminal portion 16 of a luminous tubular sign letter 17 is adapted to pass with a neat, sliding fit and so that no appreciable clearance space is left between the tubular terminal portion it? and hole it? through which dirt or insects are adapted to pass.

Each of the sign letters 1? has mounted in their terminal end portions, in accorda. ce with the standard practice, an electrode 17. These electrodes have a discharge end portion 18 at their outer end and are provided at their inner end with a pair of terminal wires 19 by means of which the respective letters are connected to the electric wiring circuit of the sign, preferably by a helically coiled connecting wire (not shown such as commonly used in the sign industry.

For the purpose of securing the insulator to the face plate It) of the sign, I employ retaining clips such as shown in Fig. 3, preferably made of spring wire. Each of these clips has a pair of terminal laterally extending ear portions 19, an inclined intermediate portion 24 and an inner transverse portion 21. The lateral terminal ear portions 19 are adapted to seat within a pair of re-entrant recesses 22 provided in the outer face of the laterally projecting annular flange 13 of the insulator. Suitably formed within the cylindrical web portion it of the insulator is a pair of re-entrant slots 23 having that portion which extends between the inner face of the said cylindrical portion and the inner end of the annular flange provided with an inclined surface indicated by the reference character 24 against which the inclined in ediate portion 2% of the clip is adapted to seat and thereby exert a pressure tending to hold the inner face of the annular flange ll snugly against the outer surface of the face plate 19 of the sign. In order that the retaining clips will be spaced as far as possible from the discharge end of the tube electrode 17 the slots 25 are located on a diametral line of the cylindrical web portion perpendicular to the diameter along which the center of hole s offset eccentrically.

As shown best in Figs. 1 and the annular flange 13 of the insulator is provided with plurality of alternating radial recesses 25 and ridges 25 to provide a gripping sur face by means of which the insulator may be rotated for adjusting the eccentric h le 15 of the insulator in proper position so as to locate the luminous gas-filled sign letter in proper relationship with the letters painted on the outer surface of the base or face plate it The manner in '-.=.-'hich the insulator is attached to the base plate is illustrated in Fig. 5 of the drawings. One of the retaining clips is placed within the slot 23, with the terminal end portions thereof seated in recesses 22 and with the insulat r held an as shown in Fig. 5, the inner end portion of the clip is inserted through the aperture 11 of the face, the lateral terminal ears 1) of the clip being seated within the recesses 22 provided in the outer fact, of the lateral flange 13 thereof and with the inner portion 21 of the clip in engagement with the inner surface of the race plate it of the sign. A similar clip is placed within the opposite slot 23 of the insulator. The second clip can be readily manipulated to insert the inner portion thereof through the aperture 11 until it is in a position such as illustrated in Fig. 5 but with the terminal end portions 19 of the end portions not seated l within the recesses 22. After the second clip has bee placed from the position such as illustrated in Fig. 5, all that is necessary is then to thrust the insulator home until the annular flange 13 thereof seats against the outer surface of the face plate in during which movement of the insulator the clip will be moved so that, as the flange l3 approaches its innermost seated engagement with the face plate, the clip will tend to swing down towards locking position. The clip may then be pushed i wardly until its terminal end portions T? will become seated within the recesses 22 in the flange of the insulator.

After the insulator 12 has been thrust home as just described, the clips will serve to hold it rotatably within the oversized apertures ll of the face plate. This will enable the pair of insulators designed to hold any particular sign letter to be rotatively adiusted within their respective apertures 11 so as to properly locate the luminous sign letter in proper relationship with the painted letters of the sign.

In locating the sign letters within the insulators the ter minal end portions 16, which contain the discharge electrodes 17 are thrust through the eccentric holes 15 a distance such that the discharge end 18 of the electrode will be located approximately at least one inch from the innermost portions of the clips where the intermediate inclined portion thereof terminates.

As will be seen from the foregoing, the provision of an eccentric hole 15 in accordance with the present invention, together with the rotative mounting of the insulator by the retaining clips, enables the luminous sign letters to be readily located in proper relationship with the painted letters of the sign. The use of the retaining clips also enables the central web portion 14 of the insulator to be made as a relatively thin section. Hence, the use of the longer clamping metal sleeves heretofore commonly employed with both the porcelain and glass insulators and which project inwardly a considerable distance beyond the face plate of the sign is thereby obviated. Therefore, it is possible with the present insulator to provide ample space between the discharge en 13 of the electrode 17 and any metal parts which are in contact with the grounded sign metal so that arcing of the high-voltage current from the electrode along a path of the dirt and foreign matter which collects on the horizontal surfaces of the prior insulators is prevented.

The importance of keeping a sufiicient distance between the metal discharge shell in the electrode and the ground metal of the sign proper cannot be overestimated. The electrostatic strain at the end 18 of the discharge shell is extremely high and the close proximity of any metal, or conductive material to metal, to this shell will result in arcing of the high-voltage current and puncturing the glass wall of the luminous tubular glass sign letter. When this occurs, consequent failure of the tube is inevitable with resultant service calls and replacement of such tubes. This electric strain can be decreased materially as the discharge point is moved away from the metal face plate of the sign. It is well known in the sign industry that wet weather intensifies the tube failures and that the number of tube failures with consequent service calls is doubled and often tripled during such wet weather. The purpose of the thin central section of the web portion of the present insulator is to offer as little horizontal surface as possible on which dirt may collect and thus form a conductive path for the high-voltage current to the metal of the sign and also to keep the insulator, and the retaining clips therefor, a maximum distance from the metal discharge end of the electrode 17 The purpose of the hole 15 near the center of, but

eccentrically located in, the web portion 14 is to hold the tube at the greatest possible distance from the grounded metal of the sign structure, while the neat fit of the tubular end 16 of the luminous letter in said hole serves to prevent the entrance of water, dirt, insects, etc.,

into the sign structure, to prevent the shifting. of the tube 5 due to the loosening of the tie wires attached to the terminals of the luminous sign. letter and displacement of the tube due to perfen nce of cleaning operations thereof, or any other cau e 01 tube shifting.

The purpose of the 0. center position of the hole 15 is to allow for necessary adjustment of the hole to properly locate the in its i ive to the letters painted on the face of the sign.

The eccentric location of the hole 155 enables the pair of insulators in wh"- @r is mounted to be rotated subst ally in to properly locate the position of the lumin sign letter. The retarng clips and the manner in which they associated with the insulator permit the insulators to be inserted from the outside of the sign face. This is of marked advantage bec use it el' a necessity o" w t i the in c ti"'. sheet metal 10: the porcelain and g s insulators employed. use of these retaining e s as hereinbefore described not nly permit t insulator to be swung position from the exterior of he sign but allow it to be freely rotated. Furthermore, the clips will allow for a ("'fference in thic es of the sheet metal that forms the face plate of the Moreover, the clips and insulators are securely locked in position 1st accidental displacement once the insulator with the clips in place are locked in place by the engagement of the terminal laterally projecting cars 19 within the recesses 22 provides in the face of the annular laterally projecting flange 13. in ii connection it will be understood that, instead of providing re-entrant recesses in the outer face of the annular flange, a pair of spaced small projecting ridges could be employed; the recesses, however, being preferred for simplicity of manufacture.

The insulators may made in standard colors so that a color matchir e color of the sign face may be chosen.

Because of the fact that the luminous tubular sign letters fit fairly snugly within the holes of the insulators and so that the terr al end portions of the luminous sign letters substant .iy fill and close said hole, the appearance of a sign will be greatly enhanced because of the eiimination of e large, unsightly open holes provided in the insulators as heretofore employed.

The converting of signs with conventional insulators to insulators of the type constructed in accordance with the present invention would be a relatively simple operation, since it is only necessary to remove the old insulator, to replace the same with the present insulator and reconnect the electric terminals 19 to the wiring circuit of the sign.

The present insulator was tested under the following conditions: A gaseous tube load of 6,700 volts was connected to a 12,600 volt transformer and a mixture of aluminum filings, dirt and grease was smeared over the entire inner of the insulator and a spray of Water was played di tly on the tubing and the insulator continuously for seventy hours without any visible effect on the insulator or the tubing and without any arc ng from the discharge end of the electrode 17 occurring. This overloading of the transformer resulted in extremely high, instantaneous voltages of approximately 30,000 volts which placed severe strain not only on the insulator but would, with the types of insulators heretofore employed, inevitably have resulted in an arcing circuit from the electrode across to the ground metal of the sign, with consequent tube failure.

To facilitate removal of the insulators, the recesses 22 in the face of annular flange 13 are preferably no deeper than half the diameter of the Wire from which the retaining clips are made, and said recesses are sufiiciently longer than the cars 19 to enable a screw driver or other suitable tool to be inserted under one of the cars 19 thereby to lift the ears out of the recesses and to the position shown at the right of Fig. 5 so that the insulator can be readily removed by a reversal of the steps hereinbefore described for attaching the insulators and clips to the sign.

While I have described and claimed a commercially satisfactory constructional example of an insulator mad in accordance with my invention and as shown in the accompanying drawings, it will, of course, be understood that changes, variations, and modifications thereof within the purview of the skill in the art may be resorted to without departing from the spirit of the invention as set forth in the accompanying claims.

1 claim:

1. A readily removable insulator for attaching a tubular vertically extending luminescent gas-filled sign letter having a horizontal terminal end portion in an oversized aperture provided in the face plate of an electric advertising sign, said insulator comprising a fiat cylindrical disk portion seated within said aperture and serving to substan. lly fill and close said aperture, said insulator having no rearwardly projecting portion extending inwardly beyond the inner face of said disk portion, said portion being provided with a through hole thro 3h which said terminal end portion projects rearwardly, said hole being of such slightly larger diameter than said terminal end portion that the latter substantially fills and close said hole, said terminal end portion having the major part of its rearward extension uncovered by said insulator whereby the connection terminals at the inner end of said terminal end portion of said sign letter are exposed and acces ib e, an annular serrated flange projecting laterally iron the o r periphcrial of s id cylindrical disk portion, and means for holding said i' ulator for rotative, but nonaxial, movement within said aperture with the annular flange thereof in abutting engagement with t.e outer surface of said face plate.

2. An insulator as set forth in claim 1 in which the periphery of said web portion is provided with a pair re-entrant diametrically opposed slots and the projecting annular flange is provided with a pair of diametrically opposed re-entrant recesses and a pair of spring "Wire retaining clips is provided, each having a pair of short lateral terminal outer end portions for seating Within said recesses, a Wide inner end portion parallel to said terminal outer ends for engagement with the inner surface of said face plate, and an intermediate portion inclined an angle to the periphery of the cylindrical web portion of said insulator received within said slots normally to hold the laterally projecting flange thereof in abutting engagement with the outer surface of said face plate.

3. An insulator as set forth in claim 2 in which the cylindrical web portion thereof is provided with an inclined surface for engagement by the intermediate inclined portion of said clip thereby to cause the latter normally to urge and hold the inner race of said lateral flange of said insulator in abutting engagement with the outer surface of the face plate of said sign.

An insulator set forth in Ila-1.1 2 in which the through hole in the cylindrical web portion is located eccentrically along a diarnetral line thereof and the slots in the annular flange are located oppositely on a diametral line extending perpendicular to said first-named diametral line.

References Cited in the file of this patent UNITED STATES PATENTS 

